An endoscope includes a handle and an insertion tube for inserting into a patient to perform diagnostic and therapeutic procedures. The insertion tube of the endoscope generally includes a bending section near the distal tip so that the orientation and position of the distal tip is steerable by a physician.
The bending section of the endoscope must be sufficiently controllable and flexible that the physician can position the tip in any necessary location within the body cavity being examined. For most endoscopes, the tip must be able to perform a 180.degree. turn in any direction. In some types of endoscopes, the tip need turn only in a left or right direction to provide the control required by the physician.
There are many different structures which can be used in constructing the bending section of an endoscope. One structure, as described in U.S. Pat. No. 3,739,770, utilized two helically wound metal strips, one of which loosely surrounds the other. The bending section is controllably steered by at least one cable extending through the tube and connecting to a control mechanism in the housing of the endoscope.
In U.S. Pat. No. 4,947,827 (the '827 patent), the bending section is comprised of a plurality of links coupled together by pivots. The main body of the links are spaced sufficiently from each other that each link may pivot about so that the entire endoscope may bend.
U.S. Pat. No. 4,869,238 (the '238 patent), to Opie et al., describes an insertion tube comprised of three concentric helical coils of thin, spring steel ribbons. The cylindrical members are formed into a D-shaped tube 94 using a conventional press, as illustrated in FIG. 5 of the '238 patent. Ribs 170 having the desired shape including the groove 122 are then coupled to the D-shaped tube 94 to provide the final, generally circular endoscope having a groove as shown in FIG. 8 of the '238 patent. A disposable channel with a disposable sheath, as described in U.S. Pat. No. 4,646,722, is then placed within the groove to provide a circular insertion tube for insertion within the human body. A bending section similar to that shown in the '827 patent may then be used at a distal end portion to permit steering o the tip.